Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck and German Center for Infection Research, partner site Luebeck, 23538 Luebeck, Germany; Max-von-Pettenkofer Institute, Ludwig-Maximilians-University Munich and German Center for Infection Research (DZIF), partner site Munich, 80336 Munich, Germany; Max-von-Pettenkofer Institute, Ludwig-Maximilians-University Munich and German Center for Infection Research (DZIF), partner site Munich, 80336 Munich, Germany; Department of Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, 82152 Martinsried, Germany; Institute of Virology, University of Bonn Medical Centre and German Center for Infection Research, partner site Bonn, 53127 Bonn, Germany; Department of Biology and Center for Integrated Protein Science, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany; Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck and German Center for Infection Research, partner site Luebeck, 23538 Luebeck, Germany; Experimental and Molecular Pathology, Institute of Pathology, Ludwig-Maximilians-University Munich, 80337 Munich, Germany. Max-von-Pettenkofer Institute, Ludwig-Maximilians-University Munich and German Center for Infection Research (DZIF), partner site Munich, 80336 Munich, Germany; vonbrunn@mvp.uni-muenchen.de.